1. Field of the Invention
The present invention relates to a photo-excited processing apparatus used to manufacture a semiconductor device or an electronic circuit and a method for manufacturing a semiconductor device by using the same, and more particularly to an improvement in irradiating a high and uniform illumination of light beam to a substrate having a large area in an efficient manner by properly setting a construction of an illumination system.
2. Related Background Art
In a manufacturing process of a semiconductor device and an electronic circuit, particularity a VLSI, a photo-excited processing apparatus has recently been used for various purposes because it principally permits low temperature processing with low damage. For example, it has been applied to cleaning and annealing, and applications to film forming and etching have been proposed.
In a manufacturing process of a VLSI, because of a large area thereof, it is required for an illumination system of the photo-excited processing apparatus that an illumination be high over an extended area of a plane to be illuminated and a distribution of illumination is uniform.
FIGS. 3, 4 and 5 show illumination systems in the conventional photo-excited processing apparatus. In FIG. 3, numeral 31 denotes light source means which comprises a light source 32 is a point light source. The reflector 33 is a parabolic mirror having a center of curvature at a light emitting point of the light source 31. The reflector 33 collects light beams radiated from the light source 32 to one-half of the space and projects them to a plane to be illuminated.
The light beams from the light source means 31 are directed to an incident plane 34a of a fly-eye lens (optical integrator) 34 having a plurality of small lenses arranged two-dimensionally. An exit plane 34b of the fly-eye lens 34 is a secondary light source plane having a uniform luminance. The light beam from the exit plane 34b is collimated by a collimating lens 35 and directed to a reaction chamber (not shown) of the photo-excited processing apparatus in which raw gas is filled, through a light transmissive window.
FIG. 4 shows only light source means 41 of an illumination system. The light source means 41 comprises a light source 42 having a plurality of bar-shaped lamps (42a, 42b, . . .) having long light emitting planes in a direction perpendicular to the plane of the drawing arranged one-dimensionally and a plurality of cylindrical mirrors (43a, 43b, . . .) each having a center of curvature on a light emitting line of the light source 42 for reflecting the light beams from the light source 42. The light beams from the light source means 41 are directed to a reaction chamber (not shown) of the photo-excited processing apparatus through a light transmissive window.
FIG. 5 shows an illumination system of a distant point light source type. The illumination system of FIG. 5 directly directs the light beams from light source means 51 which is similar to that of FIG. 3 to a reaction chamber (not shown) of the photo-excited processing apparatus through a light transmissive window.
In the illumination system of FIG. 3 which uses the fly-eye lens 34, when the light intensity of the light source 32 is raised, the fly-eye lens 34 is heated and clouded so that a transmittance is lowered. Further, when a light source which emits light beams of a wide wavelength band is used, chromatic aberration occurs from the fly-eye lens 34 and it is difficult to attain uniform illumination.
In the illumination system of FIG. 4, the light source means 41 is complex and large in size because a number of bar-shaped lamps are required. Further, when the light source means 41 is spaced from the light transmissive window in order to attain a uniform distribution of illumination, the illumination on the plane to be illuminated is abruptly lowered.
In the illumination system of the distant point light source type of FIG. 5, when the light source means 51 is spaced from the light transmissive window in order to attain a uniform distribution of illumination on the plane to be illuminated as is done in the illumination system of FIG. 4, the illumination on the plane to be illuminated is abruptly lowered.